Neutralized polycondensed vinylphosphonates

ABSTRACT

THE PRESENT INVENTION PROVIDES A PROCESS FOR FLAMEPROOFING TEXTILES WHICH COMPRISES APPLYING TO THE TEXTILES A SOLUTION CONTAINING A NEUTRALIZED, POLYCONDENSED VINYLPHOSPHONATE WHEREUPON THE NEUTRALIZED CONDENSATE IS CURED SO AS TO FORM AN INSOLUBLE, FIRE RETARDANT RESINOUS FINISH CHARACTERIZED BY ITS EXCELLENT DURABILITY.

United States Paten US. Cl. 260-928 4 Claims ABSTRACT OF THE DISCLOSUREThe present invention provides a process for flameproofing textileswhich comprises applying to the textiles a solution containing aneutralized, polycondensed vinylphosphonate whereupon the neutralizedcondensate is cured so as to form an insoluble, fire retardant resinousfinish characterized by its excellent durability.

RELATED APPLICATION This application is a continuation-in-part ofcopending application Ser. No. 23,493, filed Mar. 27, 1970 nowabandoned.

BACKGROUND OF THE INVENTION In the above noted copending application,there is disclosed a process for flameproofing textiles which comprisesthe application, thereto, of a variety of polycondensedvinylphosphonates of which the idealized formula for the preferredspecies corresponds to the formula:

wherein n is a number having a value of from about 1 to 20. The thusapplied condensate is then cured, or polymerized, so as to form aninsoluble, fire retardant resinous finish.

The above described polycondensed vinylphosphonates can be used toprovide a number of different textiles with a fire retardant finisheswhich are curable under mild conditions without any need for excessiveheating or for the use of acid catalysts. However, it has been foundthat the thus produced fire retardant finishes are often somewhatdeficient with respect to their durability upon being laundered or drycleaned. Thus, upon being Subjected to the latter operations, there maybe a considerable loss of the resinous finish from the textile substratewith a consequent diminution of its fire retardant properties.

TECHNICAL DISCLOSURE OF THE INVENTION It has now, surprisingly, beenfound that substantial improvements in the durability of the fireretardant finishes derived from polycondensed vinylphosphonates havingthe repeating structural unit:

O-GHzCHzCl which are originally produced by the condensationpolymerization of a monomeric 2-haloethyl vinylphosphonate containingacidic groups, can be obtained by affecting their neutralization bymeans of a reaction with an effective amount of an epoxide reagent priorto their use as textile finishing reagents.

The thus neutralized polycondensed vinylphosphonate is thereafterapplied to a textile substrate and then cured,

3,822,327. Patented July 2, 1974 by an appropriate means, so as to yieldan insoluble fire retardant resinous finish characterized by anoutstanding degree of resistance to laundering and dry cleaning which isin marked contrast to the durability of the finishes obtained, underidentical conditions, with the unneutralized condensates from whichthese neutralized materials are prepared. As used in this disclosure,the term vinylphosphonate is meant to include bothalpha-methylvinylphosphonates as well as alpha-unsubstitutedvinylphosphonates.

The actual preparation of the neutralized, polycon densedvinylphosphonates used in the textile finishing process of thisinvention begins with the preparation of the unnentralized,polycondensed vinylphosphonates. This is accomplished by heating abis(Z-haloethyl) vinylphosphonate, preferably, bis(2-chloroethyl)lvinylphosphonate, at a temperature suflicient to evolve an ethylenedihalide. The rate of this reaction is improved by conducting it in thepresence of catalytic amounts, e.g. from ppm. to 5%, of a basic compoundwhich may be a carbonate, bicarbonate or hydroxide of an alkali oralkaline earth metal such, for example, as sodium carbonate, potassiumcarbonate, lithium carbonate, sodium bicarbonate and calcium hydroxideor any base capable of cleaving the phosphonate ester linkage so as togenerate a phosphonate anion. Other effective bases in this systeminclude alkali halides, alkali phosphates, phosphines, quaternaryammonium bases or salts and quaternary phosphonium salts. Apolymerization inhibitor such, for example, as hydroquinone or otherphenols, may also be present in the system in a concentration of fromabout 1 to 1,000 p.p.m., by weight, of the "vinylphosphonate in order tosuppress vinyl-type, i.e. addition, polymerization during thepreparation and/or the storage of the resulting condensate.

The condensation reaction is conducted at elevated temperatures in therange of from about to about 250 C., preferably about to 220 C., whileremoving, usually by means of distillation, the ethylene dihalide, e.g.ethylene dichloride, which is formed as a by-product. The distillationis usually followed by a stripping or sparging of the reaction mixturein order to complete the removal of the ethylene dihalide by-product.The reaction may be terminated when the amount of ethylene dihalidewhich has been liberated corresponds to the desired degree ofcondensation, i.e. the number of vinylphosphonate units, in the averagepolycondensate molecule.

The main course of the above described reaction may be represented bythe following idealized equation.

In the above equation, the subscript n will have a value of from about1.2 to about 10. However, it is to be understood that is represents anaverage value since as is true in substantially all condensationpolymerizations, a more or less statistical distribution occurs. In thisdisclosure, n is hereinafter referred to as the degree of condensation.In the equation, the symbol X designates a halo radical which may beeither chloro or bromo. It is to be understood that all references tohalo groups or radicals in this disclosure are meant to encompass bothchloro and bromo groups.

However, it should be stressed that, as prepared by means of the abovedescribed reaction procedure, the polycondensed vinylphosphonates arenot precisely represented by the above given formula. Thus, theseproducts will contain some residual P(O)OH and groups which are acidicin nature and whose presence is ascribable to various side reactionswhich are, for the most part, incompletely understood. Unless theformation of these acidic groups is deliberately enhanced for reasonsand by means of procedures described hereinbelow, their presence isquite difficult to control quantitatively. Thus, these acid groupsinterfere to a substantial degree with the utility of the polycondensedvinylphosphonates. For example, they retard the curing rate when theyare utilized in the preparation of polyester resins and impart poormoisture resistance and weathering properties among their otherundesirable eflects.

The removal of this acidity is now brought about by neutralizing theseacidic polycondensates by means of a reaction with a neutralizingamount, i.e. an amount which is at least effective to neutralizesubstantially all of the acidic groups, of an epoxide reagent, i.e. areagent having one or more groups on its molecule. Such epoxide reagentsinclude C -C alkylene oxides such as ethylene, propylene, butylene,octylene and styrene oxides, epichlorohydrin, epibromohydrin, glycidol,glycidyl ethers such as the diglycidyl ether of isopropylidenediphenol,butadiene diepoxide, vinylcyclohexene diepoxide, 3,3,3-trichloro-l,2-epoxypropane, and glycidyl esters such as glycidyl methacrylate andglycidyl acrylate. Preferred for use in preparing the fire retardanttextile finishes of this invention are the polycondensedvinylphosphonates which have been neutralized by being reacted withethylene or propylene oxide, epichlorohydrin or the diglycidyl ether ofisopropylidenediphenol. The reaction may be run at a temperature of fromabout 25 to 225 0, preferably at about 50- 150 C., over a period of fromabout 0.1 to 24 hours. The reaction is usually terminated when ananalytical determination of the remaining acid groups in thepolycondensate reveals that they are present in an insignificant level.Thus, for most practical purposes, an acid number of about 10 mg.KOH/gm, or less, is the equivalent of neutrality. The precise amount ofacidity which is considered insignificant will, of course, depend uponthe particular use to which the neutralized condensate is to be put. Anyunreacted epoxide reagent dissolved in the reaction product may then beremoved by purging the system with nitrogen and/or by applying vacuum.

The thus produced neutralized, polycondensed, vinylphosphonates aresyrups whose viscosity increases with an increase in their degree ofcondensation. Although these condensates can be prepared so as to havetwenty or more phosphorus atoms per molecule, such products areextremely viscous and are not ordinarily as useful as those whereinthere are from about one to about ten phosphorus atoms per moleculesince the latter are more conveniently utilized in the textile finishingprocess of this invention. Thus, the most preferred neutralizedpolycondensates are those having an average of about 1.2 to 10, andparticularly about 1.5 to 6, phosphorus atoms per average polycondensatemolecule. A discussion of the theoretical aspects of the neutralization,with epoxide reagents, of polycondensed vinylphosphonates may be foundin the article by Kafengauz et al. on page 73 of the April 1967 issue ofSoviet Plastics.

It is to be emphasized at this point that the structures of the epoxideneutralized, polycondensed vinylphosphonates utilized in the textilefinishing process of this invention are quite diflicult to specify bymeans of precise formulae. Thus, the initial polycondensation reactioninvolving the bis(2-haloethyl) vinylphosphonate would be expected, in anidealized sense, to run as follows:

wherein n and X are as previously defined. However, since in actualexperiments, acidic groups are found by titration, the above givenformula cannot completely represent the product. Thus, titrationexperiments indicate that P(O)OH and probably P(O)-OP(O) groups arepresent. Thereafter, when the acidic groups are rendered neutral byreaction with an epoxide reagent, further uncertainty occurs in theresultant structure since experiments on simpler model compoundsindicate that the reaction between P(O)OH groups and ethylene oxides,for example, does not only yield P(O)OCH CH OH groups but actually alsoprovides P(O)O(CH CH O) CH CH OH groups wherein m is greater than zero.Further ambiguity occurs where the epoxide reagent is unsymmetrical, asin the case of epichlorohydrin or propylene oxide, since -OCH CHOHCH Rand/or OCH(CH R)CH OH structures may form; R in the latter structuresindicating alkyl groups. The fate of the anhydride linkages is also notfully understood. Thus, they can lead to P(O)--Oalkylene-OP(O) or togroups since they can be cleaved by the epoxide or by the hydroxyalkylgroups which are present in the reaction mixture. For all of thesereasons, it is preferred to describe these neutralized, polycondensedvinylphosphonate in terms of the process by which they are produced.

A small concentration of cyclic glycol phosphonate ester structures,which have acidic properties in the presence of water due to rapidhydrolysis are also believed to be in the reaction mixture. These cyclicester structures are not believed to react directly with the epoxideused for neutralizing the product, but are believed to slowly react withthe hydroxyalkyl groups engendered by the epoxide phosphonic acidreaction to form neutral noncyclic esters. The cyclic esters can also bereduced in concentration by adding an alcohol such as methanol beforethe epoxide reaction step in order to open these cyclic esters to formneutral noncyclic esters. This optional step of adding an alcohol toopen the cyclic esters does not elminate the other acidic groups. Thus,the products derived from reaction mixtures to which an alcohol has beenadded are meant to be included in the class herein described as acidicpolycondensed vinylphosphonates which are subsequently subjected to theepoxide treatment which is the subject of the present invention.

A portion of the acidity, in the form of P(O)OH groups, which is presentin the polyphosphonates prior to their neutralization, is believed to bedue to the presence of residual bis(2-haloethyl) 2-haloethylphosphonate,e.g. bis(Z-chloroethyl) 2-haloethylphosphonate, which is theintermediate commonly used in preparing the bis(2- haloethyl)vinylphosphonates from which the condensates are, in turn, prepared (seeSorstokke and Stamm, US. Pat. 3,548,040). Accordingly, it may sometimesbe desired to prepare these neutralized condensates for use in thetextile finishing process of this invention so that they have a highhydroxyalkyl content which is often useful where they are to be employedas coreactants with certain types of reagents such, for example, asaminoplasts and isocyanates, or to improve their water solubility. Thismay be accomplished by deliberately admixing a quantity of abis(2-haloethyl) 2-haloethylphosphonate with the bis(2-haloethyl)vinylphosphonate prior to the above described condensation reaction.Under these conditions the 2-haloethylphosphonate is believed to undergothermal dehydrohalogenation in situ to form a vinylphosphonate.

Thus, for each mole of the bis(2-haloethyl) phosphonate which is addedto the system in this manner, the resulting condensate 'will contain onemolar equivalent of P(O)OH or P(O)-O'P(O) groups which will, in turn,provide for about one mole of hydroxyalkyl groups in the neutralizedcondensate resulting from the process of this reaction. With respect toproportions, this embodiment of the process for preparing theseneutralized polycondensates may be carried out by the addition of thebis(2-haloethyl) Z-haloethyl phosphonate in an amount of from 0.1% up toabout 100%, by weight, of the bis(2-haloethyl) phosphonate dependingupon the hydroxyalkyl content which is desired in the neutralizedcondensate. Moreover, one may, if desired conduct a process in which thebis(2-haloethyl) 2-haloalkyl phosphonate is condensed in the completeabsence of any bis(2-haloethyl) vinylphosphonate whereupon the resultingcondensate is then neutralized in a reaction with an epoxide reagent inthe manner described hereinabove.

Another method for deliberately increasing the PO(OH) content of theacidic polycondensates and, consequently, the hydroxyalkyl content ofthe neutralized products derived therefrom, involves introducing somewater or a quantity of an inorganic acidic reagent such as a hydrogenhalide, e.g. HCl or HBr, phosphorus pentoxide or phosphoric acid in anamount equivalent to the desired acidic group content either before,during or after the polycondensation reaction.

Under the polycondensation conditions described above, a furtherelaboration of the polycondensation is possible wherein the(Z-haloethyl) vinyl phosphonate and/or its halohalide adduct precursor,i.e. 2- (haloethyl) 2-haloethylphosphonate, is condensed with at leastone compound of the structure ROP(=O)XY where R is alkyl, halogenatedalkyl and preferably methyl, ethyl, or 2-chloroethyl, and X and Y areRO- or non-interfering radicals selected from the group consisting ofalkyl, alkenyl, alkoxy, alkenyloxy, aryl, aryloxy, amino, alkyloraryl-substituted amino, or alkylene or alkylene bonded to same or toanother ROP(=O) moiety, any of which groups can bear non-interferingsubstituents such as alkoxy, cyano, carbalkoxy or carbamide. Ahomopolycondensation giving ethylenedihalide and a copolycondensationgiving R-halide as co-products can, of course, be run eithersimultaneously or consecutively thus allowing for many variations inproduct composition.

Typical examples of reactions of the copolycondensation type are:

OOHzCHzO P 0 ongonto P o C1CH2CH2O CH2: H x

where x can have a value of about 2 to about 20. and

-CH: Cl CH;=CHP (O) (OCH2CH2CD2 CHaP (O) (OCHaiP CH =CHP (O) (OCHaCHgCl)OCHzCHrOP (O) OCHa CH3 CH3 CI I As prepared by means of the abovedescribed procedures, these neutralized, polycondensed vinylphosphomatesare soluble in many organic solvents as well as in water. Thus, whilethe use of aqueous solutions comprises the most economical means ofapplication for these flame retardants, they may also, if desired, beapplied to a textile substrate while dissolved in any of the organicsolvents commonly used in the solvent finishing of textiles including,for example, trichloroethylene, dichloroethane, trichloroethane,perchloroethylene, methylene chloride, etc. and mixtures thereof.

The solutions, either aqueous or organic solvent, containing theselected neutralized condensates may be applied to textiles by the useof any desired procedure. It is merely necessary to have the neutralizedcondensate evenly absorbed throughout the mass of the textile and/ or toapply it to at least one surface thereof by means of any convenientprocedure. Thus, they may be applied by being sprayed or printed ontoone or both surfaces of the textile or, as is more frequently the case,the textile may be passed or padded through the solution while thelatter is being held in a tank or other suitable container. Such aprocess is commonly referred to as a padding technique with the solutionbeing referred to as a padding bath or padding solution.

The concentration of the neutralized, polycondensed vinylphosphonatewithin the padding bath, or other applicable solution, will be dependentupon a number of factors including the nature of the fibers whichcomprise the textile, the weight and weave of the textile, the degree offlameproofing that is desired in the finished textile, as well as othertechnical and economic considerations known and understood by thoseskilled in the art. However, it is generally desirable that the dryadd-on, i.e. the final amount of the resin finish on the textile, shouldbe in the range of from about 5 to 50%, as calculated on the dry weightof the untreated textile. This range of dry add-on will, in turn,provide the thus treated textile with about 0.5 to 10%, preferably about15%, of phosphorus as based upon the dry weight of the untreatedtextile. Again, it is to be stressed the latter limits are merelyillustrative and may be varied so as to provide a textile finish havingany desired degree of flame retardancy.

The thus applied neutralized condensate may be cured in the wet state orit may be completely or, most preferably, partially dried before curing.The mode of curing in accordance with the process of the inventionpreferably involves the use of a free radical initiated reaction inorder to induce the double bonds, i.e. the ethylenic unsaturation, ofthe vinyl groups present in these compounds to polymerizeintermolecularly so as to form a crosslinked, insoluble resin in and/oron the individual fibers which comprise the textile substrate. In thiscuring reaction, the vinyl groups in the condensate may react with eachother and/or with the cellulose. In the latter case, the reaction may bedescribed as grafting.

Free radical initiation of the desired polymerization reaction may beinduced either by the use of those chemical catalysts known as freeradical initiators and/or by the use of the actinic radiation. Suitablefree radical catalysts encompass azo compounds as well as peroxygencompounds. The latter catalysts may be used as part of a so-called redoxsystem containing a chemical reducing agent such as ascorbic acid, abisulfite or a ferrous salt, etc., in addition to the peroxygencompound. An example of a suitable peroxygen catalyst is hydrogenperoxide, which is often used in a concentration of from about 0.01 to5%, by weight, of the neutralized, polycondensed vinylphosphonate. Whereespecially rapid catalysis is desired, the use of a redox system,comprising a peroxygen catalyst in combination with one of the abovedescribed reducing agents is recommended. These two components of theredox system may be applied to the textile substrate in separateoperations in order to prevent premature cure.

Actinic radiation encompasses high energy protons and other particlescapable of initiating free radical reactions including ultravioletlight, X-rays, gamma rays, alpha rays, beta rays, i.e. electron beamradiation, and plasma, i.e. a highly ionized gas as obtained, forexample, in corona discharges from a high voltage terminal. A preferredsource of actinic radiation involves the use of an electron beam, i.e.beta radiation, since equipment adaptable for textile mill use isreadily available and is eminently suited for rapid, continuousprocessing. In any event, regardless of the type of actinic radiationthat is used, it should be applied in a dosage which is sufiicient toinitiate polymerization. Thus, in the case of electron beam radiation,suitable dosages are typically in the range of 0.1-10 megarads.

Where a cure is induced by the use of a free radical catalyst, theselected catalyst may be conveniently activated by heating up to about180 C. but, preferably in the range of from about 60 to 160 C. so as toavoid any thermal damage to the textile. Heating may, if desired, beaccomplished by the use of steam or hot gases. Alternatively, thecatalyst can be activated by applying a reducing agent of the typedescribed herein above to the cloth either before or after aplying theflame retardant and catalyst. The catalyst may also be activated byactinic radiation.

Generally, the rate of cure of a catalytically initiated cure isadversely influenced by the presence of atmospheric oxygen. Therefore,for an optimum cure rate, it is advantageous to exclude oxygen by use ofan inert gas which can be steam, nitrogen, carbon dioxide or the like. Aparticularly convenient means for accomplishing this effect is toconduct the final drying of the finish at the cure temperature so thatthe steam being evolved forms an air-excluding blanket. In the textilemill this is easily accomplished by passing the treated textile from thepadder over heated metal cylinders or cans at such a rate andtemperature as to initiate curing while some moisture still remains.

When actinic radiation is used, either alone or in combination with afree radical catalyst, it is only necessary to expose the textile to abeam from a radiation source. If desired, this can be done at ambienttemperatures and with great rapidity, e.g. from about 0.1 seconds toseveral minutes, thus sparing the textile from thermal damage. A furtheradvantage of radiation curing is the fact that since catalysts andheating are not required, the textile is generally found not to haveundergone any serious degradation of its physical properties such ascolor, tear strength, and abrasion resistance. In addition, a raditioninduced cure is generally not as seriously affected by the presence ofoxygen in the system as is a chemically induced cure. Moreover, it hasbeen found that by using radiation to affect the cure, the resultingfinish will be tightly cured, i.e. extensively crosslinked, so as toprovide it with greater durability to laundering and dry cleaning.

The exposure to actinic radiation can be conveniently conducted bypassing the textile through the beam which may be produced, for example,by a bank of ultraviolet lamps, corona-discharge points, a cobalt-60source, an X-ray source or an electron beam source. Reasonablyhomogeneous radiation flux is desirable where an electron beam is used.Thus, the beam can be transversely scanned across the textile at a rapidrate so as to evenly irradiate all points thereon. If desired, asuitable mechanical arrangement of rollers can be employed so that thetreated textile can be made to repeatedly pass through the radiationfield, thereby facilitating more complete use of the available radiationflux while also obtaining more uniform irradiation.

The use of actinic radiation initiation does not generally require theuse of a chemical activator. However, the efficiency of the radiationcan frequently be improved by use of such an activator. Suitableactivators for this purpose include ketones, such as acetone or benzoin;

polycyclic hydrocarbons, such as polyphenyl; and, azo compounds such asazobisisobutyronitrile. Where an electron beam is used, the applicationof about 0.1-10 megarads generally suffices to affect the desired cure.

The resulting cure, or polymerization, of the neutralized, polycondensedvinylphosphonate which is induced by either a catalyst and/or actinicradiation generally takes place on the surface of the individual fiberswhich comprise the textile substrate. However, where the fiber is onewhich can readily absorb the neutralized condensate such, for example,as the cellulosic fibers, the polymerization can also take place withinthe body of the fibers. Moreover, as has been noted, in some cases theresulting polymer network may be grafted, or chemically bonded, onto thetextile fiber molecules. However, such grafting is not crucial to theattainment of a durable, flame retardant finish.

The irradiation of the textile is usually carried out subsequent to theapplication of the neutralized condensate, although in the case ofcellulosic fibers which can be irradiated so as to form stable, longlived free radical sites, the neutralized condensate can be appliedsubsequent to irradiation whereupon it will proceed to cure by graftingonto the cellulose.

An advantage of the products resulting from the reaction of epoxideswith the acidic vinylphosphonate polycondensation products is that theseproducts contain alcoholic OH groups. The presence of these groups makespossible modes of curing in place of or in addition to curing by meansof free radical polymerization of the vinyl groups. Thus, these reactionproducts may be cured by polyfunctional reagents capable of reactingwith the alcoholic OH groups, examples of such reagents being diorpolyisocyanates and anhydrides of dibasic or polybasic acids. Moreover,where the alcoholic OH groups are primary, as in the case where theepoxide employed is ethyleneoxide, curing may be effected withpolymethylolated amino compounds such as dimethylolurea, diorpolymethylol melamine, dimethyloluron or dimethoxymethyluron,dimethylolidhydroxy and ethyleneurea. Where the sole means of curing isto be by the use of such a chemical reaction of the primary alcoholic OHgroup with a methylol amino compound, the use of dirnethyloldihydroxyethyleneurea is highly preferred for this purpose.

A further means of curing these products involves addition reactions,with compounds having more than one NH group, to the double bonds of thevinylphosphonate structures. Thus, these products may be cured byreaction with ammonia, primary amines, and polyamines of the typecommonly used to cure epoxy resins, including dicyandiamide andguanidine. The epoxide-neutralized products have an advantage, in thisrespect, over the precursor acidic polycondensed vinylphosphonates inthat amine curing agents do not form useless and undesirable salts withthese epoxide-neutralized products.

The process of this invention may, if desired, include the use of otherfree radical curable, i.e. polymerizable, comonomers along with theselected neutralized, polycondensed vinylphosphonate as a means ofachieving variations in the properties of the resulting treatedtextiles. The thus added optional comonomers form copolymers with theneutralized condensate during the curing, or polymerization of thecondensate. Suitable comonomers for use in conjunction with theneutralized condensate include:

(1) Monomers containing an amide nitrogen such as acrylamide,methacrylamide, N-mcthylolacrylamide, N- methylolmethacrylamide,diacetonylacrylamide, methylene bisacrylamide,triacryloylhexahydrotriazine, N vinylpyrrolidone and cellulose-graftedN-methylolacrylamide, the use of the latter monomer being disclosed inUS. Pat. 3,434,161. The use of these amide nitrogen containingcomonomers at a concentration of up to about 6 molecules per each vinylgroup of the neutralized condensate,

9 permits a more economical finish, particularly with cellulosic fibers,since less of the more costly phosphonate monomer needs to be used inorder to achieve a given level of flame retardancy. From the lattergroup of monomers, the use of acrylamide is preferred.

(2) Monomers containing more than one polymerizable double bond such,for example, as the glycol diacrylates, the glycol dimethacrylates,methylene bisacrylamide, triacryloylhexahydrotriazine, triallylphosphate, dialkyl allylphosphonate and triallyl cyanurate. By usingthis class of comonomers, the crosslink density of the resulting finishcan be increased, thereby enhancing its durability with respect to wearand laundering.

(3) Monomers contributing to flame retardancy, i.e. monomers havingphosphorus, bromine or chlorine atoms in their molecules including, forexample, vinyl and vinylidene halides such as vinyl chloride, vinylbromide, vinylidene chloride, vinylidene bromide, vinylidenechlorobromide and chloroprene; triallyl phosphate; diallylphosphonate;dialkyl vinylphosphonates such as diethyl vinylphosphonatebis(2-chloroethyl) vinylphosphonate or its polycondensation products;and, in general all of the unsaturated phosphonate monomers disclosed inmy copending applications Ser. Nos. 23,493 and 23,499 both filed Mar.24, 1970.

(4) Monomers contributing to surface quality, i.e. hand, softness,flexibility, smoothness of tactile quality, gloss, and abrasionresistance, for example hydroxyalkyl acrylates or methacrylates,alkoxyalkyl acrylates or methacrylates, long-chain alkyl acrylates ormethacrylates, vinyl long-chain alkyl acrylates or methacrylates, vinyllong-chain alkyl ethers, vinyl esters of fatty acids or fluorinatedakanoic acids, or the like.

When utilized in the process of this invention, the above describedoptional comonomers can be present in the system in an amount of up toabout 6 molecules per each vinyl group of the required neutralized,polycondensed vinylphosphonate.

It should be noted, at this point, that the use of the term crosslinkedin describing the cured, fire retardant resins resulting from thepolymerization of the selected neutralized polycondensedvinylphosphonate in the textile finishing process of this invention willindicate to those skilled in the art that these resins possess athree-dimensional configuration or network rather than a simple linearor branched structure of the type found in non-crosslinked copolymers.Thus, such cross-linked polymers may be further characterized by thefact that they will not lose more than about 20% of their total weightupon being extracted with methanol in a Soxlet extractor. Moreover, asused in this disclosure, the term fire retardant is intended'to refer tothat particular property of a material which provides it with a degreeof resistance to ignition and burning. Thus, a fire or flame retardanttextile is one which has a low level of flammability and flame spread.This property may be conveniently evaluated by means of any of thestandard flame retardancy tests such, for example, as the so-calledvertical char length flame test described in AATCC (American Associationof Textile Chemists and Colorists) 34-1966.

The textile finishing process of this invention is compatible with awide variety of other textile finishing operations which can be carriedout prior, simultaneous with, or subsequent to the process of thisinvention. These other operations include application of durable press,softening, anti-static, abrasion resistance, water-repellent,soil-release and antimicrobial finishes as well as bleaching, dyeing,printing, flocking, and texturing. Thus, the finishing formulations ofthis invention may also optionally contain other types of ingredientsknown in the textile fiinshing art. For example, water and soilrepellents, optical brighteners and colorants, softening agents such aspolyethylene emulsions, hand-modifying agents, buffering agents, pH-controlling agents which may be acidic or basic, emulsified waxes,chlorinated paraffins, polyvinyl chloride, polyvinylidene chloride,homoand copolymers of the alkyl acrylates and other resinous finishingagents may be added in conjunction with the finishing agents of thisinvention. And, where an extremely high degree of flame retardance isrequired, it is possible to employ systems containing antimony oxide anda resinous binder, particularly one containing chlorine, such as achlorinated paraffin or polyvinyl chloride, along with the neutralized,polycondensed vinylphosphonates required in the process of thisinvention.

All types of textiles may be treated by means of the process of thisinvention so as to provide them with durable, fire retardant finishes.Thus, one may treat textiles derived from natural fibers such as cotton,wool, silk, sisal, jute, hemp and linen and from synthetic fibersincluding nylon and other polyamides; polyolefins such as polypropylene;polyesters such as polyethylene terephthalate; cellulosics such asrayon, cellulose acetate and triacetate; fiber glass; acrylics andmodacrylics, i.e. fibers based on acrylonitrile copolymers; saranfibers, i.e. fibers based on vinylidene chloride copolymers; nytrilfibers, i.e. fibers based on vinylidene dinitrile copolymers; rubberbased fibers; spandex fibers, i.e. fibers based on a segmentedpolyurethane; vinal fibers, i.e. fibers based on vinyl alcoholcopolymers; vinyon fibers, i.e. fibers based on vinyl chloridecopolymers; and, metallic fibers. Textiles derived from blends of any ofthe above listed natural and/or synthetic fibers may also be treated bymeans of the process of this invention.

As used in this disclosure, the term textile or textiles is meant toencompass woven or knitted fabrics as well as non-woven fabrics whichconsist of continuous or discontinuous fibers bonded so as to form afabric by mechanical entanglement, thermal interfiber bonding or by theuse of adhesive or bonding substances. Such nonwoven fabrics may containas much as of wood pulp as well as conventional textile fibers in whichcase part of the bonding process is achieved by means of hydrogenbonding between the cellulosic pulp fibers. in nonwoven fabrics, thefinishing agents of this invention can function not only as flameretardant finishes but can also contribute to the interfiber bondingresin component. This dual role can also be played by the finishingagents of this invention in fabric laminates where the finishing agentcan at the same time serve as the interlaminar bonding agent and as theflame retardant. In both of these systems, i.e. non-woven fabrics andlaminated fabrics, the finishing agents of this invention can also beblended with the usual bonding agents such, for example, as acrylicemulsion polymers, vinyl acetate homoand copolymer emulsions,styrene-butadiene rubber emulsions, urethane resin emulsions, polyvinylchloride emulsions, vinyl chloride-alkyl acrylate copolymer emulsions,polyacrylates modified by vinyl carboxylic acid comonomers and the like.

It should also be noted, at this point, that in addition to being usedto provide flame retardant finishes for textiles, the above describedneutralized, polycondensed vinylphosphonates can be used forflameproofing a variety of otherwise flammable polymeric substrates suchas cellulose in the form of paper, wood, plywood, chipboard, jute,batting and the like; urethane foams, coatings, and elastomers;aminoplast resins and phenolic resins as well as their composites withpaper, wood flour and the like; alkyd coatings and molding resins; and,paints and varnishes derived from natural or synthetic resins.

The following examples will further illustrate the embodiment of thisinvention. In these examples all parts given are by weight unlessotherwise noted.

EXAMPLE I This example illustrates the preparation of a neutralizedvinyl polyphosphonate suitable for use in preparing durable, fireretardant textile finishes by means of the process of this invention.

1 1 Part A A total of 8 moles (1864 gms.) of bis(2-chlorovinyl)vinylphosphonate, 8 gms. of sodium carbonate and 0.2 gms. oft-butylhydroguinone are heated at a temperature of 170-185 C. for 3hours and then sparged with nitrogen gas until a total of 475 gms. ofethylene dichloride has been distilled off. This corresponds to theformation of a condensation product having the idealized averageformula:

H H C=CH On titration to a Congo red end point, this condensate is foundto have an acid number of 70 mg. KOH/ gm. which indicates that asubstantial number of acidic groups are present in the product.

Part B The above described condensate is then neutralized by the passageof about 50 gms. of ethylene oxide into this product over a period of 4hours while the system is at a temperature of 120125 C. The system isthen sparged with nitrogen to remove dissolved, unreacted ethyleneoxide. The thus neutralized condensate is a light yellow syrup having anacid number less than 5 mg. KOH/gm., and containing 17.8% P.

EXAMPLE II This example illustrates the preparation of a durable, fireretardant textile finish with a neutralized, polycondensedvinylphosphonate by means of the novel process of this invention. Italso provides a comparison with the results obtained, under identicalconditions, using the unneutralized condensate from which theneutralized material is prepared.

A series of four 3" x 10" samples of a white polyester: cotton (65:35)cloth having a weight of 2.6 z./sq. yd. are padded with the fourdifferent solutions whose compositions are set forth in Table I,hereinbelow. The thus treated cloths are then dried and cured at 160 C.for a period of 3 minutes. The color of the treated cloths is notedwhereupon their flammability is then evaluated by means of the verticalchar length test, as described in AATCC 34-1966, in which a strip of thefinished cloth is suspended in its vertical dimension so that its loweredge is maintained above the top of a Bunsen burner having a 1.5" highflame for a period of 12 seconds. The length of the resulting char isthen measured. Thus, a shorter char length of about to 7 inches isindicative of a greater degree of fire retardancy while a char length oflonger than about I inches is unacceptable for most applications.

The char length test procedure is then repeated upon four additionalsamples of the treated cloth which, in this instance, have beensubjected to a series of five detergent washes. A comparison of the charlengths obtained with the various finished cloths before and after thefive detergent washings thus serves to provide an evaluation of theirdurability. Table II, hereinbelow, provides the data obtained in theseevaluations.

TABLE I.CONTENTS OF PADDING BATHS Percent solids in bath TABLEIL-EVALUATION RESULTS Fabric treated in bath No. 1 No. 2 No. 3 No. 4

Percent dry add-0n 0t finish on dry wt. of cloth 42.8 52 44.6 52.

olor Tan Lt. tan. Lt. tan.-. White. Char length before wwh 3 4.3 4.8

(inches). Char length after wash BEL BEL 5.5 5.5.

(inches).

*BEL: Burned over its entire length.

The above data clearly indicate that the fire retardant finishesprepared from the neutralized polycondensed vinylphosphonates whose useis required in the process of this invention are substantially moredurable than the finishes prepared from the unneutralized condensates.

EXAMPLE III This example again illustrates the preparation of flameretardant textile finishes with neutralized polycondensedvinylphosphonates.

Padding baths having the compositions described the following table areprepared:

Percent solids in bath No. 1 No. 2 No. 3 No.4

A polycondensed bls(2-chloroethyl) vinylphosphonate containing 18.4% I?having a. degree of condensation of 2.8, which has been neutralized withethylene oxide to an acid number of 1.5 mg. KOH/gm 15 15 15 The abovedescribed condensate but in unneutralized form and having an acid numberof 56 mg. KOH/gm 15 Aerylarnide (eomonomer) 11.25 11.25 11.25 11.25Oetyl phenoxypolyethylene ethanol (wetting agent) 0.05 0.05 0.05 0.05Potassium persultate (catalyst) l 1 1 1 Urea ufter) 5 Sodium bicarbonate(butler). 5 5 Water 17.70 17. 70 17. 70 17. 70

Polyethylene cloth swatches are padded in these baths, dried in air andthen cured in a steam press at 380 F. for 3 minutes The samples are thensubjected to an accelerated laundring by being boiled for one hour withan aqueous solution containing 0.5% Na CO and 012% of soap.

The cloths treated in baths Nos. 1-3, which contain neutralizedcondensate, are found to be non-burning under the conditions of ASTM'D2863 while the cloths treated in bath No. 4, which contains theunneutralized condensate, burn in air under these same conditions.

EXAMPLE IV This example illustrates the preparation of a series ofethylene oxide neutralized, polycondensed vinylphosphonates havingdifferent degrees of condensation and also demonstrates their use forthe flameprodfing of textiles.

Part A A mixture of 22,350 gms. of bis(2chloroethyl) vinylphosphonate(the crude product resulting from thermal rearrangement oftris-Lchloroethyl phosphate), 48 gms. of sodium carbonate and 1 gm. ofdi-tert-butylhydroquinone is heated at 180-185 C. over six hours until5,555 gms. of ethylene dichloride is distilled off. The reaction mixtureis then cooled to 122-126 C. and 1,050 gms. of ethylene oxide is passedin. Previous to the introduction of the ethylene oxide, the acidity ofthe batch is found, by titration of a small sample to a bromophenol blueend point with 0.1 N NaOH, to be 1.14 milliequivalents per gram. Afterthe ethylene oxide treatment, the acidity found by means of thisanalysis is nil. The small amount of unreacted, i.e. excess, ethyleneoxide remaining at the completion of the reaction is removed by spargingwith nitrogen. The product is a pale yellowish liquid containing 17.4% Pwhich corresponds to a degree of condensation of about 2.4.

. 13 By controlling the percentage of ethylene dichloride which isformed and distilled out from the reaction mass, two analogous productsare prepared, one containing 16.05%, P, and having an average degree ofcondensation of 1.8, and the other containing 18.7% and having anaverage degree of condensation of.3.0.

Part B vSwatches of cotton fabric having a weight of 3.2 oz./ yd." areadded in three baths each of which contains one of the three condensateswhose preparation is described in PartA hereinabove. The treatedswatches are air dried for 15 minutes and then cured by passage, for 5minutes, over a rotating can which is at a temperature of 280-300 F. Theflammability of the thus treated cloths is evaluated before and after 5detergent washes by determining their Limiting Oxygen 'Index (LOI) bymeans of the procedure described by Fenimore and Martin in the November1966, issue of Modern Plastics. In brief, this proceduredirectly-relates flame retardancy to a measurement of the minimumpercentage concentration of oxygen in a oxygenznitrogen mixture whichpermits the sample to burn; the LOI being calculatedas follows:

2] IOAHNA Thus, a higher LOI is indicative of a higher degree of flameretardancy with a value of about 26-27 being considered a commerciallyuseful degree of flame retardancy.

The following table presents the result of this evaluation.

Percent solids in bath No. 1 No. 2 No. 3

Neutralized condensate having a degree densatlon of 1.8 and containing16.05% Neutralized condensate having a degree of condensation of 2.4 andcontaining 17 .4% P; Neutralized condensate having a degree ofcondensation of 3.0 and containing 18.7% P Aerylamide (comonomer) Octylphenoxy polyethyleneoxy ethanol (wetting agent) Potassiumpersulfate(catalyst) Percent dry add-on LOI before washing.- L01 after washingsEXAMPLE V This example illustrates the preparation of a number ofadditional neutralized, polycondensed vinylphosphonates and their use inthe preparation of fire retardant textile finishes.

Part A The preparative procedure of Part A of Example I, hereinabove, isrepeated with the exception, in this instance, that 70 gms. of propyleneoxide is used in carrying out the neutralization reaction by being fedinto the system by means of a tube beneath the liquid surface. Thisneutralization is carried out at 125-135 C. over a 2 hour periodwhereupon the system is held at 125-135 C. for one hour and then spargedwith nitrogen to remove excess propylene oxide. The resultingneutralized condensate is a pale yellow syrup having an acid number ofless than 5 mg. KOH/gm.

When 22 parts of this product are substituted for the condensate used inBath No. 1 of Example IV, hereinabove, cotton cloths which are padded inthis bath are found to have excellent flame retardancy properties bothbefore and five detergent washes when evaluated by means of the LOIprocedure.

Part B The preparative procedure of Part A of Example 1V hereinabove, isrepeated with the exception, in this instance, that 300 gms. of Epon828, which is sold by the Shell Chemical Company and which mainlycomprises the diglycidyl ether of isopropylidenediphenol, is

used in carrying out the neutralization reaction which is carred out ata temperature of C. over a three hour period. The resulting product is apale yellow syrup having an acid number below 10 mg. KOH/gm.

When 22 parts of this product are substituted for the condensate used inBath No. 1 of Example IV, hereinabove, cotton cloths which are padded inthis bath are found to have excellent flame retardancy properties bothbefore and five detergent washes when evaluated by means of the LOIprocedure.

Part C The following procedure describes the preparation of an ethyleneoxide neutralized, polycondensed bis(2- chloroethyl) vinylphosphonate ofhigh hydroxyalkyl content by the addition of bis(2-chloroethyl)2-chloroethylphosphonate to the system prior to the condensationreaction.

A mixture of 932 gms. (4 moles) of his (2-chloroethyl) vinylphosphonate,537 gms. (2 moles) of bis(Z-chloroethyl) 2-chloroethylpl1osphonate, 5gms. of sodium carbonate, and 1 gm. of di-tert-butylhydroquinone isheated at -200 C. over 10 hours with nitrogen purging for the last 1hour in order to remove a total of 660 grams of ethylene dichloride (6.7moles). The acidity of the product at this point is 3.3 milliequivalentsper gram (Acid NO.= mg. KOH/gm.). Ethylene oxide is then passed in at110-125 C. until the product is neutral to bromophenol blue indicator.The hydroxyalkyl content of this product is determined bythe standardacetylation technique indicating a hydroxy number of 91.6 mg. KOH/ gm.

When 22 parts of this product together with 15 parts ofN-methylolacrylamide are substituted for the condensate and theacrylamide used in Bath No. l of Example IV, hereinabove, cotton clothswhich are padded in this bath are found to have excellent flameretardancy properties both before and five detergent washes whenevaluated by means of the LOI procedure.

Part D The following procedure describes the preparation of a propyleneoxide neutralized co-polycondensate of 2-chloroethyl vinylphosphonateand tris-(2-chloroethyl) phosphate.

A total of 0.54 moles (145.3 gms.) of bis(Z-chloroethyl)vinylphosphonate is heated at 2l0-216 C. until 0.54 moles of ethylenedichloride is evolved. This product is shown, by titration of a smallsample with NaOH, to be mainly the 2-chloroethyl monoester ofvinylphosphonic acid. This intermediate is then heated with 1.79 moles(513 gms.) of tris(2-chloroethyl) phosphate and 3 gms. of sodiumcarbonate at 183-190" C. until 2.14 moles (2l1.7 gms.) of ethylenedichloride is evolved. The resultant product is found, by titration of asmall sample, to contain 0.7 moles of acid. In order to neutralize thisacidic product, 50 gms. (0.86 moles) of propylene oxide, whichrepresents a small excess over the theoretical, is added, with stirring,at 120-125 C. over a one hour period. The thus produced product is alight yellowish syrup which is found to be neutral upon titration withNaOH using bromophenol blue as an indicator.

Analysis-Found: P, 15.6%; C1, 16.5%; Hydroxy number=49 mg. KOH/gm. AcidNo.=less than 0.1 mg. KOH/ gm.

When 22 parts of this product are substituted for the condensate used inBath No. 1 of Example IV, hereinabove, cotton cloths which are padded inthis bath are found to have excellent flame retardancy properties bothbefore and five detergent washes were evaluated by means of the LOIprocedure.

Variations may be made in proportions, procedures and materials withoutdeparting from the scope of this invention as defined in the followingclaims.

What is claimed is:

1. A padding bath comprising a solution of at least one neutralized,polycondensed vinylphosphonate, said neutralized, polycondensedvinylphosphonate comprising the substantially neutral product resultingfrom the reaction at about 25 to 225 C. between a neutralizing amount ofan epoxide reagent selected from the group consisting of C -C alkyleneoxides, styrene oxide, epichlorohydrin, epibromohydrin, glycidol,diglycidyl ether of isopropylidenediphenol, butadiene diepoxide,vinylcyclohexene diepoxide, 3,3,3-trichloro-1,2-epoxypropane, glycidylmethacrylate and glycidyl acrylate, and an acidic polycondensed vinylphosphonate having as its repeating structural unit the group:

said acidic, polycondensed vinylphosphonate resulting from the heatingof a monomeric bis(2-haloethyl)vinylphosphonate so as to effect itscondensation polymerization to a polycondensed vinylphosphonate havingfrom of ethylene oxide, propylene oxide, epichlorohydrin and thediglycidyl ether of isopropylidinediphenol.

4. The padding bath of claim 1, wherein said acidic, polycondensed,vinylphosphonate is prepared by the condensation polymerization ofbis(2-chloroethyl) vinylphosphonate. 1

References Cited FOREIGN PATENTS 202,126 11/1967 U.S.S.R. 260-928 ANTONH. SUTIO, Primary Examiner US. Cl. X.R.

PR-wBd UNITED STATES PATENT OFFICE CERTIFICATE 1 OF CORRECTION iatent N3 .522 327 Dated Julv 2 .1974

InwentOr(s) I D. Weil It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Errors to be listed:

Col. 5, line 55, change "P (O)PCH2CH2CL) 3" to -P (O) (OCH2CH2 Cl) Col.5, line: 71, change "-CH CI" to --CH C l-- i I Col. 5, line .71, change(OCH CH OP (O)-O CH CI-T. -O-P (O) CH I, CH=CH I 2 tO' (OCH CH OP(O)O-CH CH -O-P (O) Col. 7, line 25, change "aplying to -applying-;

Col. 12, line 37, next to "Water" in the Table change each occurrence of',l 7.70" to --67.70; v I I 7 Col. 12, line 42, change "3 minutes' to 3minut es.;

Col. 12, line 43, change "laun'dring" to --laundering-;

Col. 13, line 67, and Col. 14, lines 9, 39 and 70, insert --afterbefore"five".

Signed and sealed this 18th day of February 3975.

(SEAL) Attest:

H C. MARSHALL DANN RUTH C. MASON Commissioner of Patents ArrestingOfficer and Trademarks

